Dear aspirant,

The marks that you have to score in JEE can't be said for sure as the rank versus marks keep varying based on the difficulty level of the paper. Yet, based on previous year trends, a crl of 15K - 20K will help you get into IIT. For getting this rank usually, one should get a mark above 130 out of 300. CRL does not matter but your category rank matters and that is what will decide your chances of getting admission into IISc.

Hope this helps.